This is a continuing investigation of fluid dynamics as related to commonly encountered problems in vascular surgery. Our objectives are to define the nature of the flow disturbance which occurs at anastomoses, stenoses, points of curvature and within crimped dacron grafts; to determine the relationship between flow disturbances and hyperplasia at a vascular anastomosis, and to determine changes in fluid energy which occur as a function of vascular geometry. Flow visualization studies will be performed using visual dye streamlines. These will be analyzed and recorded by a videotape system. Regions of boundary layer separation, high shear, and low shear will be defined. Fluid energy will be measured. Energy losses will be calculated and stored on a microcomputer system. In vitro studies will be performed of models of anastomoses, stenosis within anastomoses, tapered, crimped, and curved vascular grafts. Anastomotic hyperplasia will be studied in dogs using light and scanning electron microscopy of the vessel wall and casts of the anastomotic lumen. Plastic models of in vivo anastomoses will be made and used for flow visualization and correlation of flow disturbances with anastomotic hyperplasia. This work will diminish technical errors in vascular surgery by defining fluid energy losses in models of clinical vascular grafts and providing a basis for accurate judgement. It will diminish delayed failures of reconstruction by defining the flow disturbance responsible for anastomotic hyperplasia and providing guidelines for minimizing this disturbance during arterial reconstruction.